The Boulton Paul P.99 was a design for a twin-boom fighter produced in response to an Air Ministry specification for a manoeuvrable fighter.
Specification F.6/42 called for a fighter with a high rate of climb (4,500ft/ min to 20,000ft), good acceleration and good manoeuvrability. Boulton Paul's first design was the P.98, a tail first pusher that was judged to be over-weight. This was followed by the P.101, a staggered biplane with cantilevered wings and the cannon carried within the spats for non-retractable main wheels.
After both of these projects were rejected by the Air Ministry, Boulton Paul submitted two designs with lower project numbers.
The P.99 was a twin boom fighter, powered by a Rolls-Royce Griffon that powered contra rotating pusher propellers. The pilot's cockpit was in the nose, and was covered with a bubble cockpit. In case of emergencies the pilot was to escape downwards, using a system that involved jettisoning part of the lower front fuselage. The armament would have been carried in the nose. The low mounted wings had an equal span central section, and tapering outer panels. The twin booms went back from the wings, so were below the level of the fuselage. The horizontal tail surface connected the booms, and there was a single vertical tail in the centre. The undercarriage was of the conventional tail wheel type, with the retractable main wheels at the front of the booms and the tail wheel below the vertical tail.
The P.99 was to be armed with either one 47mm cannon, with a 20mm cannon in either side, or two 20mm cannon with a 40mm cannon on either side.
In September 1942 all of the designs submitted to F.6/42 were examined at the RAE, and all of the Boulton Paul designs were dismissed for being too futuristic.